This invention relates to patient interfaces particularly though not solely to nasal mask for use in providing CPAP therapy to patients suffering from obstructive sleep apnoea (OSA).
In the art of respiration devices, there are well known a variety of respiratory masks which cover the nose and/or mouth of a human user in order to provide a continuous seal around the nasal and/or oral areas of the face such that gas may be provided at positive pressure within the mask for consumption by the user. The uses for such masks range from high altitude breathing (i.e., aviation applications) to mining and fire fighting applications, to various medical diagnostic and therapeutic applications.
One requisite of such respiratory devices has been that they provide an effective seal against the user""s face to prevent leakage of the gas being supplied. Commonly, in prior mask configurations, a good mask-to-face seal has been attained in many instances only with considerable discomfort for the user. This problem is most crucial in those applications, especially medical applications, which require the user to wear such a mask continuously for hours or perhaps even days. In such situations, the user will not tolerate the mask for long durations and optimum therapeutic or diagnostic objectives thus will not be achieved, or will be achieved with great difficulty and considerable user discomfort.
Where such masks as those used above are used in respiratory therapy, in particular treatment of obstructive sleep apnea (OSA) using Continuous Positive Airway Pressure (CPAP) therapy, there is generally provided in the art a vent for washout of the bias flow or expired gases to the atmosphere. Such a vent may be provided for example, as part of the mask, or in the case of some respirators where a further conduit carries the expiratory gases, at the respirator. The washout of gas from the mask is essential to ensure that carbon dioxide build up does not occur over the range of flow rates. In the typical flow rates in CPAP treatment, usually between 4 cm H2O to 20 cm H2O, prior art attempts at such vents have resulted in excessive noise causing irritation to the user and concentrated flows of gases irritating any bed partners.
Various approaches have been developed in the prior art to attempt to reduce the noise when CPAP therapy is provided. For example, in PCT Patent Application No. WO98/34665 it has been proposed that the vent include a resilient plug with rounded edges at the apertures to reduce noise. In PCT patent application no WO00178382 a vent is provided with a semi annular flap. However, these prior art methods are not entirely satisfactory in eliminating the extra noise created by a vent at the mask.
It is an object of the present invention to attempt to provide a nasal mask which goes some way to overcoming the abovementioned disadvantages in the prior art or which will at least provide the industry with a useful choice.
Accordingly in a first aspect the invention consists in a device for delivering a supply of gases to a user comprising:
a patient interface, in use in fluid communication with said supply of gases and supplying said gases to said user, and
outlet means integrated with or attached to said patient interface including at least one outlet vent and a removable diffusing member in use covering said vent, said removable member in use diffusing a substantial portion of the expired gases of said user.
In a second aspect the present invention consists in a CPAP system for delivering gases to a user including a pressurised source of gases, transport means in fluid communication with said pressurised source adapted to convey said gases, and a patient interface in fluid communication with said transport means in use delivering said gases to said user, said patient interface including:
outlet means having at least one outlet vent, and a removable diffusing member covering said vent, said outlet means in use passing a substantial portion of the expired gases of said user.
In a third aspect the present invention consists in removable diffusing member for a gases delivery patient interface, said patient interface including at least one vent, said removable member adapted to be juxtaposed in use on or over a vent, said removable member adapted to in use pass a substantial portion of expired gases from a user flowing out from a vent.
To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.
The invention consists in the foregoing and also envisages constructions of which the following gives examples.